What are the common causes of P20C3?

A short to ground on the reductant heater C control wire. An open in the reductant heater C power feed. A failed reductant heater C element. Incorrect heater C installation.

Read the reductant heater C control circuit on a scan tool. Test the heater C control wire for a short to ground. Check the heater C power feed for an open. Measure reductant heater C resistance. Replace reductant heater C if it tests out of range. Clear the code and retest.

P20C3

Reductant Heater C Control Circuit Low

System: Fuel and air metering (P code)
Lamp: Check Engine Light
Category: Powertrain - Fuel/Air Metering

What it means

P20C3 means Reductant Heater C Control Circuit Low.

Check these first

A short to ground on the reductant heater C control wire
An open in the reductant heater C power feed
A failed reductant heater C element
Incorrect heater C installation

What to do next

Read the reductant heater C control circuit on a scan tool
Test the heater C control wire for a short to ground
Check the heater C power feed for an open
Measure reductant heater C resistance
Replace reductant heater C if it tests out of range
Clear the code and retest

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Updated

Generic SAE J2012 definition. Last updated 2026-10-10.